Panoramic aerial camera



Dec. 8, 1964 c. LYSLE PANORAMIC AERIAL CAMERA 2 Sheets-Sheet 1 FiledJan. '7, 1963 Dec. 8, 1964 G. LYSLE 3,160,082

PANORAMIC AERIAL CAMERA Filed Jan. 7, 1963 2 Sheets-Sheet 2 UnitedStates Patent 3,1 0, 582 PANQRAMPC AERIAL Gordon Lysle, Greenlawn, N.Y.,assignor to Camera and instrument Qorpnratiou, a corporation of DelawareFiled Xan. 7', i963, No. 249,593 Claims. Cl. 95-125) This inventionrelates to panoramic aerial cameras and particularly to such camerassuitable for use in aerial photographic reconnaissance.

In aerial photographic reconnaissance, the use of a panoramic camerawith some fOlIl'l oi image-notion compensation has found wideapplication. In such a camera, the film is generally transported past anexposure slit in the focal plane of the camera lens in a directiontransverse to the direction of flight of the aircraft. it is necessaryto provide some mechanism for compensating for the apparent motion ofthe image at the focal plane, due to the motion of the aircraft. If theaxis of the optical system of the camera is maintained in a fixedattitude, then the apparent image motion is substantially constant andthe problem of image-motion compensation is not difficult.

However, for panoramic aerial photography, particularly at relativelylow altitudes, it becomes advantageous to use some form of opticalscanner and the well-known multi-dove prism scanner has been foundparticularly suitable for this purpose. However, such a prism is rotatedat uniform angular velocity so that the apparent image velocity at thefocal plane varies over a wide range from a maximum, when the opticalaxis is vertical, to a minimum as the optical axis approaches thehorizon. l-leretofore, there has been no satisfactory method of cornpensating such cyclically varying apparent image motion.

It is an object of the invention therefore, to provide a new andimproved panoramic aerial camera including an optical scanner which isparticularly suitable for use in photographic reconnaissance work, inwhich the apparent image velocity at the focal plane varies over a widerange of values over the scanning cycle.

It is another object of the invention to provide a new and improvedpanoramic aerial camera including an optical scanner and includingmechanism for effectively compensating for the cyclically varyingvelocity of the image motion at the focal plane.

In accordance with the invention, there is provided a panoramic aerialcamera comprising a lens holder including a lens, a film transport forintermittently moving film in the focal plane of the lens and includinga friction roller having an active perimeter substantially equal to thelength of a frame of film, a continuously rotatable optical scanneradapted to be disposed ahead of the lens for scanning the scene to bephotographed, and an imagemotion compensating mechanism including meansfor sinusoidally oscillating the lens holder substantially parallel tothe axis of rotation of the scanner.

Further in accordance with the invention, there is provided an opticalsystem for a panoramic aerial cmiera including a lens and a lens holdercomprising a continuously rotatable optical scanner adapted to bedisposed ahead of said lens for scanning the scene to be photographedand an image-motion compensating mechanism including means forsinusoidally oscillating said lens holder substantially parallel to theaxis of rotation of said scanner.

For a better understanding of the present invention, together with otherand further objects thereof, reference is had to the followingdescription, taken in connection with the accompanying drawings, whileits scope will be pointed out in the appended claims.

further includes ir holder 3,lfifi,fi82 Patented Dec. 8, 1964 iceReferring now to the drawings:

FIG. 1 is a schematic exploded perspective view of a panormic aerialcamera structure embodying the present invention;

HG. 2 is a perspective view of the image-motion compensating mechanismof the system of FIG. 1;

PEG. 3 is a cross-sectional detail view of the apparatus of FIG. 2,while FIG. 4 is a longitudinal sectional detail view of the apparatus ofHG. 2.

Referring now to FIG. 1 of the drawings, there is illustrate-d, inperspective, the essential structure of a panoramic aerial camera, theframe and casing being omitted for the sake of clarity. This structureincludes a lens holder Iltl including one or more lens elements 11,which may be of conventional construction, and an exposure slit plate 12disposed in the focal plane of the lens system. The structure alsoincludes a film transport for intermittently moving film in the focalplane of the lens system and past the exposure slit plate 12, although,for clarity of illustration, the exploded view of PEG. 1 shows the lenselement 11, the slit plate 1 2, and the film widely separated. Thisfilin transport includes a pair of friction rollers l3, 13 each havingan active perimeter substantially equal to the length of a frame offilm. The film transport further includes a film-talrc-up spool 14, afilm supply spool 15 having a friction brake llfirz, and a continuouslyrotatable constant-speed driving mechanism for the film transport.

The driving mechanism for the film transport includes a continuouslyrotatable constant-speed motor '16 which, through suitable gearing,pulleys l7, l8, and a friction drive puck 19, engages the stock of filmon the take-up spool 14. By this driving mechanism, film is taken up ata constant or metered rate, irrespective of the diameter of the filmstock on the spool M.

The friction rollers lit, 13 for intermittently advancing the film pastthe exposure slit plate 12. are, as illustrated, disposed in the generalvicinity of the exposure slit and are driven by the motor lid throughsuitable gearing mechanism. Each of the rollers 13 has an effectivedriving engagement with the film over substantially onehalf of itsperiphery. Specifically, each of these rollers is undercut oversubstantially one-half of its periphery so as to disengage it from thefilm during the interval between frarnes when the film does not moveacross the exposure slit but is being taken up from a take-up loop 2dand is being stored in a supply loop 21. For clarity, the loops 2.9 and21 are shown extending laterally although, actually, they constitutefree loops falling into slack boxes provided for that purpose. Thedriving engagement between the rollers 13, i3 and the film is maintainedby spring-biased pinch rollers Z2, 22 While the feeding of film into thesupply loop 21 during the interval between frame exposures is effectedby a friction roller 23 and coopera ing pinch rollers 24, 2d and 25, 25.The relative dimensions of the drive puck 1.9 and the rollers 13, 13 aresuch that the intermittent motion of the film past the exposure slit hasan average velocity equal to the peripheral velocity of the puck Thepanoramic camera structure of FIG. 1 al o comprises an optical systemincluding a continuously rotatable optical scanner 26 disposed ahead ofthe lens system in the lens holder ill for scanning the sceneto bephotographed. "Preferably, as illustrated, the scanner includes a pairof dove lenses 2?, 27 mounted in a suitable holder driven at constantspeed by the motor in through a suitable gear mechanism. The opticalsystem e-motion compensating mechanism including for sinusoidallyoscillating the lens substantially parallel to theaxis of rotation ofthe scanner 2d, period of such oscillation onehalf of the period ofrotation of the scanner. This imag a motion compensating mechanism isdriven by a shaft 29 continuously rotatable at a speed which is doublethat of the shaft driving the scanner 26.

The image-motion compensating mechanism is shown in more detail in FlGS.2, 3, and 4, reference being made to FIG. 2 for the general layout ofthe mechanism elements and to FIGS. 3 and 4 for the details ofconstruction of the several elements, the elements in FIGS. 3 and 4corresponding to those in FIG. 2 being identified by the same referencecharacters. Referring now to FIG. 2, the image-motion compensatingmechanism 28 includes an annular member 31 pivotally mounted on theinput shaft 29 specifically, as shown in FIG. 3, pivoted tran verselythereto by means of a pivot pin 32 passing through an enlargement 29a ofshaft 29 so that it is rotatable therewith and is normally coaxialtherewith. The member 31 has a pair of axially extending arms 33, 33provided with axially extending cam slots 3d, 3d inclined to the axialplane of the member 3E.

The image-motion compensating mechanism further comprises a universalsupport for mounting the mechanism 28 from a frame element 35 of thecamera. universal support includes an inner gimbal ring 1% in which themember 31 is rotatably supported, as by means of the antifrictionbearings 37 (FIG. 4). The universal support also includes an outergimbal ring 33 secured to the lens holder 19 and shown as beingstructurally integral therewith. The outer gimbal ring 38, is, asillustrated, pivotally mounted in the frame 35.

The image-motion compensating mechanism further comprises means fortilting the axis ofthe rotatable member 31 relative to that of the shaft29, thereby sinusoidally to oscillate the outer gimbal ring 33 and thelens holder 10 to compensate for the apparent image motion. The tiltingmeans comprises a cam actuator including a rotatable element 39 axiallyslidable along the shaft 29 but rotatable therewith and having aprojecting pin d9 engaging the cam slot 34-. The tilting means alsoincludes a nonrotatable element 41 in which the rotatable element 39 isjournalled and means for adjusting the axial position of the elements 39and 4-1 to adjust the axis of the rotatable member 31, this latter meansbeing in the form of a pivoted lever 42 having a slotted end 43 engaginga pin 44 projecting from the member 4-1.

It is believed that the operation of the panoramic aerial camera and itsimage-motion compensating mechanism will be clear from the foregoingdescription. Referring again to FIG. 1, as the motor 16 continuouslyrotates the friction rollers l3, 13, they intermittently engage the filmand advance it the length of one film frame. During the motion of thefilm past the exposure slit plate 12, the lens holder ill is oscillatedsinusoidally substantially parallel to the scanner 26 (as describedhereinafter), this sinusoidal motion compensating for the apparent imagemotion at the focal plane due to the motion of the aircraft on which thecamera is carried, the motion of the aircraft being assumed to beparallel to the axis of rotation of the scanner 26. The scanner 26 iseffective in a wellknown manner to sweep the field of view past theexposure slit of the plate 12 synchronously with the motion of the filmso as to expose a franc of film. Concurrently, the sinusoidaloscillation of the lens holder rd compensates for the apparent imagemotion due to the transverse motion of the aircraft. It will beunderstood that if the optical axis of the lens system were maintainedvertical, the motion of the lens holder iii should be linear. However,as the scanner 26 exposes the film to an element of the objectapproaching the horizon, the apparent image motion is much less. It hasbeen established that the variation in this apparent image motion is asubstantially sinusoidal function of the angular position of the scanner26 so that it may be compensated by a sinusoidal motion of the lensholder ill. While theoretically this motion should be rectilinear andparallel to the axis of the scanner 26, it has been found that, in thelimited The motion required, the arcuate movement of the lens holder toapproximates to an adequate degree a rectilinear movement substantiallyparallel to the axis of the scanner 26.

Upon movement of the film past the exposure slit by one frame, therollers 13, 13 disengage the film so that the film at the exposure slitremains stationary for approximately one-half of the rotation of therollers 13, 13. During this interval, nevertheless, the driving puck 19continues to take up film from the take-up loop 29 while the frictionroller 23 feeds film into the supply loop 21. The dimensions of thedriving puck 19, friction rollers 13, and the driving roller 23 are suchthat the constant film velocity at the take-up spool 14 and the supplyspool 15 is equal to the average velocity of the film at the exposureslit, the difference between the instantaneous velocities during theexposure period being made up by taking film from or adding film to thetake-up loop 2t) and the supply loop 21, as required.

Since the scanner 26 effects two complete scansions of the field of viewfor each rotation, the period of oscillation of the lens holder it)should be one-half that of the period of rotation of the scanner 26.

Referring now again to FIGS. 2, 3, and 4 of the drawings, it will beseen that if the position of the operating lever 42 is such that the pin40 engages the cam slot 34 at its root, which lies in the axial plane ofthe rotatable member 31, as shown in FIG. 2, the member 31 and itsassociated inner gimbal ring 36 will be coaxial with the shaft 29 andthere will be no oscillation of the outer gimbal ring 38 and lens holderill and no imagemotion compensation. Upon adjustment of the lever 42 totilt the axis of the member 31 and inner gimbal ring 36 relative to theaxis of the shaft 29, as illustrated in FIG. 4, it can be shown that asinusoidal oscillation is imparted to the outer gimbal ring 38 and itsintegral lens holder til, the amplitude of this sinusoidal oscillationdepending upon the position of the adjusting lever a2, and the law ofvariation of the amplitude of such oscillation with displacement of thelever 42 being determined by the configtu'ation of the cam slot 34.Therefore, by adjusting the lever 42, the amount of image-motioncompensation can be varied in any desired manner, for example, directlywith variations in the speed of the aircraft and inversely withvariations in its altitude.

While there has been described what is, at present, considered to be thepreferred embodiment of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein, without departing from the invention, and it is, therefore,aimed in the appended claims to cover all such changes and modificationsas fall within the true spirit and scope of the invention.

What is claimed is:

l. A panoramic aerial camera comprising:

(a) a lens holder including a lens;

(1)) a film transport for intermittently moving film in the focal planeof the lens and including a friction roller having an active perimetersubstantially equal to the length of a frame of film;

(c) a continuously rotatable optical scanner adapted to be disposedahead of said lens for scanning the scene to be photographed;

(d) and an image-motion compensating mechanism including means forsinusoidally oscillating said lens holder substantially parallel to theaxis of rotation f said scanner.

2. A panoramic aerial camera comprising:

(a) a lens holder including a lens;

(1;) a film transport for intermittently moving film in the focal planeof the lens and including a friction roller having an active perimetersubstantially equal to the length of a frame of film;

(c) a continuously rotatable multiple-dove optical scanner adapted to bedisposed ahead of said lens for scanning the scene to be photographed;

(d) and an image-motion compensating mechanism including means forsinusoidally oscillating said lens holder substantially parallel to theaxis of rotation of said scanner.

3. An optical system for a panoramic aerial camera including a lens anda lens holder comprising:

(a) a continuously rotatable optical scanner adapted to be disposedahead of said lens for scanning the scene to be photographed;

(b) and an image-motion compensating mechanism including means forsinusoidally oscillating said lens holder substantially parallel to theaxis of rotation of said scanner.

4. An optical system for a panoramic aerial camera including a lens anda lens holder comprising:

(a) a continuously rotatable multiple-dove optical scanner adapted to bedisposed ahead of said lens for scanning the scene to be photographed;

(b) and an image-motion compensating mechanism including means forsinusoidally oscillating said lens holder substantially parallel to theaxis of rotation of said scanner.

5. An optical system for a panoramic aerial camera including a lens anda lens holder comprising:

(a) a continuously rotatable double-dove optical scanner adapted to bedisposed ahead of said lens for scanning the scene to be photographed;

(b) and an image-motion compensating mechanism including means forsinusoidally oscillating said lens holder substantially parallel to theaxis of rotation of said scanner, the period of such oscillation beingone-half the period of rotation of said scanner.

References Cited in the file of this patent UNITED STATES PATENTS1,502,401 Sandell July 22, 1924 1,586,071 Cooke May 25, 1926 2,393,534Hineline Jan. 22, 1946 2,471,715 Becote May 31, 1949 2,899,882 WylieAug. 18, 1959

1. A PANORAMIC AERIAL CAMERA COMPRISING: (A) A LENS HOLDERS INCLUDING ALENS; (B) A FILM TRANSPORT FOR INTERMITTENLY MOVING FILM IN THE FOCALPLANE OF THE LENS AND INCLUDING A FRICTION ROLLER HAVING AN ACTIONPERIMETER SUBSTANTIALLY EQUAL TO THE LENGTH OF A FRAME OF FILM; (C) ACONTINUOUSLY ROTATABLE OPTICAL SCANNER ADAPTED TO BE DISPOSED AHEAD OFSAID LENS FOR SCANNING THE SCENE TO BE PHOTOGRAPHED; (D) AND ANIMAGE-MOTION COMPENSATING MECHANISM INCLUDING MEANS FOR SIMUSOIDALLYOSCILLATING SAID LENS HOLDER SUBSTANTIALLY PARALLEL TO THE AXIS OFROTATION OF SAID SCANNER.